1. Field of the Invention
The present invention relates to a receiver and related method, and more particularly to a receiver for echo and crosstalk cancellation and related receiving method.
2. Description of the Prior Art
In the existing wired network, a transceiver employs a hybrid circuit to exchange signals with external transmission wires. For example, the transceiver for realizing an Ethernet IEEE 802.3 local area network (LAN) protocol, set forth by the Institute of Electrical and Electronics Engineers, exchanges signals with four twisted pair wires. When the hybrid circuit transmits a signal, part of the signal was reflected to the transceiver, thereby causing so-called echo and crosstalk. Therefore, a typical transceiver needs a device to deal with echo and crosstalk problems.
Please refer to FIG. 1, which is a schematic diagram of a transceiver 10 according to the prior art. The transceiver 10 includes a hybrid circuit 12, a twisted pair wire 14, a local transmitter TX and a local receiver RX. Through the twisted pair wire 14, the transceiver 10 transmits and receives signals with a remote transceiver. The local transmitter TX includes a digital to analog converter for converting the signals from digital to analog form and outputting a transmission signal STX to the hybrid circuit 12. In general, the local transmitter TX operates with multiple transmission channels. The local receiver RX includes an analog to digital converter for converting a reception signal SRX from the hybrid circuit 12 from analog to digital form. The hybrid circuit 12 is utilized to split single signaling path of the twisted pair wire 14 into a receiving and a transmitting path. In addition, the hybrid circuit 12 is also used for diminishing the magnitude of the signals outputted by the local transmitter TX.
When the hybrid circuit 12 processes the transmission signal STX, part of the transmission signal STX couples to the reception signal SRX, or part of the transmission signal STX outputted to the twisted pair wire 14 is reflected to the local receiver RX due to resistance mismatch, thereby causing echo. Furthermore, the local transmitter TX is usually responsible for transmission of multiple channels. Crosstalk occurs in the local transmitter TX when a signal of a transmission channel couples to a signal of another transmission channel and further couples to reception signal SRX. In general, the local receiver RX utilizes an analog-to-digital converter (ADC) to receive the reception signal SRX, and is equipped with rough echo and crosstalk cancellation functions for converted signals. However, amplitude of the reception signal SRX possibly exceeds the acceptable receiving range of the ADC since echo and crosstalk can enlarge the amplitude of the reception signal SRX. In this situation, the reception signal SRX is clipped by the ADC, causing failure in echo and crosstalk estimation of the local receiver RX.
It is therefore an important objective to design a low-cost receiver capable of efficiently canceling echo and crosstalk.